EFFECT OF BETA-BLOCKER TREATMENT IN DILATED CARDIOMYOPATHY WITH BRADYARRHYTHMIAS

This study was performed to evaluate whether beta-blocker therapy was effective in patients with nonischemic dilated cardiomyopathy (DCM) an d bradyarrhythmias supported by pacemaker implantation, Beta-blocker t herapy is useful for some patients with DCM, especially those with rap id heart rate or residual nonfibrotic myocardium in the left ventricle , but no data exist on whether beta-blocker therapy is useful in patie nts with DCM and bradyarrhythmias. The effectiveness of beta-blocker t herapy was prospectively evaluated in patients with DCM and bradyarrhy thmias supported by pacemaker implantation and compared with those wit hout these arrhythmias, Beta-blocker therapy was started in 63 patient s (45 men, 18 women, aged 11-83 years) with DCM, in whom 7 had bradyar rhythmias and 56 did not. These bradyarrhythmias were atrioventricular block, sick sinus syndrome and atrial fibrillation with slow heart ra te. Of the 56 patients without bradyarrhythmias, 42 (75%) (group 1) re sponded to beta-blocker therapy, but 5 of the 7 with bradyarrhythmias (71%) (group 2) also responded. Left ventricular end-diastolic dimensi on was reduced (6.5+/-0.6 cm to 5.6+/-0.5 cm; p<0.0001 in group 1; 6.6 +/-0.8 cm to 5.5+/-0.2 cm; p<0.02 in group 2) and left ventricular fra ctional shortening was improved (13+/-4% to 27+/-7%; p<0.0001 in group 1; 12+/-4% to 29+/-10%; p<0.05, in group 2) to the same degree in bot h groups. These results indicate that beta-blocker therapy for DCM is effective not only in patients without bradyarrhythmias but also in th ose with bradyarrhythmias supported with pacemaker implantation.